Single chamber Mg/Ca analyses of Globigerinoides ruber for paleo-proxy calibration using femtosecond LA-ICP-MS

• Main Authors: Fischer, Alexa, Schiebel, Ralf, Jochum, Klaus Peter, Heins, Lena, Arns, Anthea I., Aardema, Hedy M., Slagter, Hans, Calleja, Maria Ll., Levy, Noy, Stoll, Brigitte, Walter, David, Weis, Ulrike, Repschläger, Janne, Haug, Gerald H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature 2024
• Subjects: North Atlantic
• Online Access: https://hdl.handle.net/20.500.11850/678209; https://doi.org/10.3929/ethz-b-000678209

Mg/Ca is an independent proxy in paleoceanography to reconstruct past seawater temperature. Femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry (fs-LA-ICP-MS) was employed to determine the Mg/Ca composition of tests (shells) of the planktic foraminifer species Globigerinoides ruber albus (white chromotype) and G. ruber ruber (red/pink chromotype) sampled alive from the temperate to subtropical eastern North Atlantic with the research sailing yacht Eugen Seibold. Mg/Ca data are compared to (i) the measured in-situ temperature of ambient seawater, (ii) average mixed layer temperature, and (iii) sea surface temperature (SST). The pooled mean chamber Mg/Ca from each plankton tow site exhibits a positive relationship with SST. Two chamber-specific calibrations are derived, which are consistent with previous calibration equations for comparable paleo-archives. The results confirm fs-LA-ICP-MS as reliable method for determining Mg/Ca in G. ruber, and both the penultimate and antepenultimate chambers of adult specimens may provide comprehensible Mg/Ca temperatures of the surface ocean. ISSN:2052-4463